Occurrence of sulfated galactans in marine angiosperms: Evolutionary implications. Glycobiology 2005

We report for the first time that marine angiosperms (seagrasses) possess sulfated polysaccharides, which are absent in terrestrial and freshwater plants. The structure of the sulfated polysaccharide from the seagrass Ruppia maritima was determined. It is a sulfated D-galactan com-posed of the following regular tetrasaccharide repeating unit: [3-b-D-Gal-2(OSO3)-1!4-a-D-Gal-1!4-a-D-Gal-1!3-b-D-Gal-4(OSO3)-1!]. Sulfated galactans have been described previously in red algae and in marine inver-tebrates (ascidians and sea urchins). The sulfated galactan from the marine angiosperm has an intermediate structure when compared with the polysaccharides from these two other groups of organisms. Like marine invertebrate galac-tan, it expresses a regular repeating unit with a homo-genous sulfation pattern. However, seagrass galacta